A number of states have recently enacted legislation requiring that yard waste, consisting essentially of grass clippings and leaves, be composted rather than buried in landfills. Since most of this yard waste is collected in plastic or paper bags, in order to compost this yard waste in large metropolitan areas, an immense quantity of yard waste must be removed from the bags and the yard waste sorted from the bags.
These new requirements are not been met by any existing inventions. In Robb, U.S. Pat. No. 1,916,531; a cement sack is carried upward by a bucket attached to a conveyor, inverted over a cutting wheel while being held by penetrating members and dumped into a container. This operation can only cut a single bag open at a time and requires that the bag be relatively sturdy in order to be held inverted by penetrating members. Further, the contents must be relatively dense to simply be spilled out of an inverted container.
In Moriarty, U.S. Pat. No. 3,447,706 a bag opening and emptying machine uses reciprocating knives driven by pistons across and through the bottom of a single filled bag supported by a number of rods. These rods are vibrated by a separate mechanism to cause material within the bag to fall through the rods. A set of bag ejecting tines interleaved with the rods are raised after the bag is emptied to eject the bag. In Cerroni, U.S. Pat. No. 3,891,105; spikes are used to draw a bag against a single knife to cut the bag open.
In Hafner et al., U.S. Pat. No. 4,119,227 a rotary knife arranged between two belts cuts bags carried in series by the belts past the knife. In Mueller et al, U.S. Pat. No. 4,278,383 pins extending outward from a drive chain carry filled bags horizontally through the machine into a cutting disk mounted upon and driven by a shaft. This machine makes a cut through the a single bag at a time, and has no special provision to keep the bag material from the cutting disk shaft.
In Bennison et al., U.S. Pat No. 4,504,183 a bag opening machine has an endless conveying band provided with spikes which conveys a series on bags impaled on the spikes in single file individually past cutting disks. After being cut the contents are emptied into receiving means while the bags are carried along until further until the bags are released by retracting the spikes. In Frisz, U.S. Pat. No. 4,515,509 bags are carried by a conveyor in series to a plurality of bag opening stations. Each station includes a driven chain loop with a plurality of outwardly extending fingers which engage the bags as they go past and either pierce the bags or lift them so the bag weight causes the fingers to pierce the bags. The bags also fall onto a conveyor belt which in combination with the piercing effects bag opening and content removal.
In Bennison, U.S. Pat. No. 4,725,184 bags are carried in series past rotating slitters to be cut into an upper and a lower half. Screening means are provided such that the contents can fall through but the bag halves cannot. In Lewis, U.S. Pat. 4,798,508 filled bags are carried in series by and between a pair of rotating drums, having several rows of rigid spikes, past a fixed blade, which slits the bag in half to empty the contents. Each empty bag half is carried on one of the rotating drums to apoint where the spikes move away to release the empty bag half. In Crane, U.S. Pat. No. 4,995,770 bags are placed within a receptacle which is pivotably attached to the rear end of a refuse truck. The receptacle is movable between an upright position and an inverted position over the truck bed. While in the upright position filled bags are placed within the receptacle which has a grate-like structure consisting of a plurality of laterally spaced bars above a rupturing mechanism in the form of generally parallel drums having circumferential rows of cutting teeth which can protrude through the grate. Bags placed within the receptacle have the end ruptured by these cutting teeth which are then be removed manually. After the bags are removed the receptacle containing the yard waste is inverted over the track. The capacity of this apparatus is small since a major portion of the operation is manual, and further there is no attempt to sort the small bag pieces resulting from the cutting teeth from the yard waste.
None of these inventions provide the immense capacity necessary to process the amount of bagged yard waste in large metropolitan areas. In the prior art in general bags are processed in sequence which automatically limits the maximum processing rate whereas in the instant invention a number of bags can be slashed open at the same time. In addition, most of these prior inventions make no provisi for sorting the bags from the material while those that do are also greatly limited in the speed in which they can separate the two, either because part of the sorting is manual or because of the intrinsic slow nature of the process used.